class Phone:
    IMEI = None      #序列号
    producer = None     #厂商
    __current_voltage = None    #当前电压，私有变量
    
    def call_by_5g(self):          #私有方法
        if self.__current_voltage >= 1:
            self.__keep_single_core()
            print("5g通话已开启")
        else:
            print("通话失败，电量不足")
        
    def __keep_single_core(self):
        print("让CPU以单核模式运行以节省电量")
        
phone = Phone()
# phone.__keep_single_core()
# phone.__current_voltage = 33
phone.call_by_5g()